This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The overall objective of this research project is to investigate the utility of photodynamic therapy (PDT) for the treatment of malignant brain tumors (gliomas). The project is a close and integrated multi disciplinary collaborative effort of various institutions in he United States and Norway. The participating parties are: The Department of neurosurgery, Rikshospital, the Laser microbeam and medical program (LAMMP) facility at the Beckman Laser Institute and Medical Clinic (BLI), University of California, Irvine (UCI), California USA the Department of health physics at the University of Nevada, Las Vegas (UNLV), Nevada USA. and the Departments of surgical oncology, and pathology the Norwegian Radium Hospital.Oslo Norway. The aim of previous investigations was to determine the utility of photodynamic therapy in combination with ionizing radiation or concurrent hyperthermia in the treatment of glioblastoma multiforme. The effects of light dose, gamma radiation dose, temperature and photosensitizer type on human glioma spheroids have been investigated in detail. The project also investigated the PDT effect of ALA-ester and repetitive PDT treatments during the past few years with several publications resulted from the study.